The invention relates to materials to be used in liquid chromatography. Liquid chromatography (LC) is a powerful tool in a separation of ionic and neural compounds. Four main types of chromatography are responsible for majority of small molecules separations: Normal phase (NP); Reverse phase (RP), Ion-exchange and ion-exclusion, Typically, each mode of separation requires specifically tailored stationary phase; this is why a significant number of columns is required to cover different types of analytical applications. Occasionally, a stationary phase can perform in two modes of separation; for example, a cyano-stationary phase can be used in reverse phase and normal phase separation modes. [1]. However, this phase has very poor hydrophobic properties and, consequently, a limited application in RP separation. Aminopropyl columns that can also be used as ion-exchange and NP separation media [2] have the same insufficient hydrophobic properties. Even when a stationary phase demonstrates good hydrophobic properties—usually due to a polymer based supporting material—it cannot be used as RP material due to low capacity, poor RP reproducibility, and lower efficiency.
In addition, now manufacturers are offering different brush type columns with embedded polar groups [3] to create an additional interaction (besides RP) between a column stationary phase and an analyte. This allows to improve column efficiency for polar compounds, resolve closely eluted compounds and, sometimes, change column selectivity. With polar embedded groups, it is possible to prevent column collapse or dewetting in pure aqueous mobile phase [4].
However, there still is a problem of having many different stationary phases, each of them for specific separation purposes; the significant numbers of similar columns available on a market from tens of manufacturers creates confusion among end users.
The presented invention is based on the provision of a new liquid chromatography stationary phases with specific arrangement of charge bearing functional groups. The groups are chemically attached to the supporting material but are shielded from direct interaction with mobile phase by an additional layer of permeable material that is also chemically be used for all four main mode of separation and additionally allows performing a wide variety of separations previously not attainable.
The invention introduces a new and improved approach to liquid separation stationary phase for use in liquid chromatography and provides methods for preparation of such liquid separation stationary phase.